Spring motors comprising telescopically mounted piston-cylinder arrangements, wherein a compression spring device is employed to apply pressure to a confined reservoir of hydraulic fluid in order to effect extension of a piston rod are well known, as evidenced for instance by U.S. Pat. Nos. 3,145,055; 3,145,056; and 3,182,564. Structurally similar devices have also been employed in numerous other environments, as generally illustrated by U.S. Pat. Nos. 2,747,860; 3,143,757; 3,381,952; 3,442,051; 3,625,540 and 3,963,101.